A simplified method for observatio n al prediction of land subsidence based on the settlement records being previously observed at locations of the objective area was proposed in the previous paper for the use of Geographical Information System (GIS). However, no consideration of variations in groundwater level (GWL) was taken into proposal of the method. In the present paper, however, an effort was made to realize this using the time series analysis. The variations of settlements with time predicted by using the proposed two methods available for the cases with and without consideration of fluctuation in GWL were compared with those observed at locations in the objective area. In comparison with a method without consideration of fluctuation in GWL, better agreement in the case with consideration was recognized between predicted and measured settlements versus time relations. In particular, it was made clear that the proposed method succeeds in predicting the acceleration of settlements with elapsed time during the period of water shortage. The results predicted using the method proposed are visualized as the hazard map using a Geographical Information System (GIS). Based on the visualized map with GIS application, a possible monitoring system is presented for prevention of damage due to land subsidence.

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In this paper, using several observed groundwater levels, the method to identify the distribution of the lower boundaries of aquifer and the groundwater parameters in unconfined aquifer simultaneously is proposed. The genetic algorithm is used to minimize the difference between the observed and the calculated groundwater levels. Here the distribution of the lower boundaries of aquifer is expressed by linear interpolation of several lower boundaries on the grids and the groundwater parameters are constant in the region. This method is applied to the simulation regions of aquifer and coastal aquifer to discuss the availability.

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Groundwater samples were collected in Miyako Island and in the southern part of Okinawa Island from February to November 1999, and their estrogenic activity was measured by means of a recombinant yeast assay. Five out of eight sites in downtown or in the vicinity of residences and two out of fourteen rural sites showed estrogenic activities that ranged from 0.2 to 2.0 ngL^-1 (17β-estradiol (E2) equivalent). Further sampling was continued at one site in the downtown of Miyako Island for ten times between July 2000 and June 2001. Correlation between the fluctuation of the estrogenic activity and that of the concentrations of some ions such as Na⁺ was found at this site. E2 concentration of groundwater samples from Miyako Island in 1999 was also measured by means of ELISA. E2 was detected from all the samples with estrogenic activity.

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Chemical compositions of thirteen g r o und and spring waters, and alteration minerals from aquifers above 100 m depth were analyzed to clarify the water-mineral interactions conducted to the chemical composition of the waters in the southern area of Noda city, Chiba, Japan. There are three aquifers (the first, second and third aquifers) whose water compositions are Ca-HCO₃ type. Ca²⁺ and HCO₃^- contents gradually increase with depth. Saturation indices of aragonite and calcite, and pH of the waters gradually increase with depth. Kaolinite and plagioclase are found in the aquifers. Based on these data and presence of shell fossils in the Kioroshi and Kamiiwahashi Formations, the increases of Ca²⁺ and HCO₃^- contents with depth are mainly interpreted by the following tw o mechanisms: (1) dissolutions of calcite and aragonite as the shell fossils, and (2)formation of kaolinite by weathering of plagioclase.

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“A Launcher -type” well which has t wo ports vertically or horizontally is proposed. It has a port for recharge of washing water against contaminated area at the upper part of the well or either side of it. Another port for withdrawal of contaminated water is located at the lower part or the other side. A launcher-type well can wash out contaminant in the vadose zone and saturated zone water. In this paper, the well for recharge is dug closely to a well for pumping up (withdrawal) at a shallow layer of underground in contamination area of chromium (VI) and the experiments for practical functions of “semi Launcher-type wells” which substitutes for Launcher-type wells have been conducted by these two wells that were dug in accordance with the field on the basis of a series of the indoor models.
Although the wells could not beset closely to the hot spot, experiments showed the effect of washing out residual chromium (VI) in the vadose zone at the beginning of recharge. Therefore, if these wells are constructed at the exact site of contaminant, performance of washing the contaminated underground is to be significant.
In addition, a water flood method is experimented by rech a rge from the upstream well combined with the downstream well for withdrawal. This method might be included in “flushing” was experimented on purpose to wash out of contaminant in the wide area by recharged water from the well that was dug in the upstream of hot spot. Its effect was confirmed by this experiment.
On the whole, about 1.8kg of chromitim (VI) was collected during six months in this experiments which are composed of pumping, semi launcher wells and water flood operations.
Although the grasp of long-term decrease of the concentration and the material balance were not shown, the result in this paper shows one step advance in practical use of the series of launcher-type devices that have been initiated with indoor experiments.
A foundation of semi launcher type wells was obtained for the development of more effective remediation method in-situ against the contamination throughout the underground. Then it would be useful to establish a numerical analysis in three dimensions in the next step.

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